Product design and engineering

In the present study, the authors performed a dynamic analysis of the desmodromic timing system, where the valve lifter is realized by conjugate cams, using a methodology of modal synthesis to examine the effects of the deformability of the principal parts, and evaluating the deformations and vibrations of the components under various operating conditions. With this aim, a virtual 3D model and a multibody calculation program were used in a concentrated parameter model, requiring the choice of numerous parameters that greatly affect the results of the analysis. It was therefore important that, within the variability range of these parameters, the values adopted rendered the behavior of the analytical model as close as possible to that of the real system. Finally, the need to evaluate some of the more important aspects of the dynamic system (such as values of clearances, stiffnesses and damping at contacts, and stiffnesses and damping of shafts and belt) made it necessary to validate the model through comparison with experimental trials conducted to determine the valve motion and to measure the strain on the distribution belt.

Keywords: Desmodromic timing system , Dynamics , Flexible bodies , Modal synthesis

The aim of this paper is to understand how the Theory of Inventor's Problem Solving (TRIZ) may be applied in the development of product-service combinations. The authors have analyzed TRIZ modules and tools under a PSS (Product Service System) perspective to extract some principles of particular interest for their development. Basing on the outcomes of such investigation, the authors propose a framework for the use of TRIZ-based tools in product-service design.

Keywords: Product-Service Systems , TRIZ

The introduction of deterministic NC grinding and polishing operations, in the manufacturing of free-form glass components for precision optics, requires the characterization of surface topography evolution as a function of process parameters. In this work, a model based on Reye's wear hypothesis is proposed for the assessment of surface roughness prediction as a function of operating parameters, in the deterministic polishing process of glass moulds. According to Reye's hypothesis, the removed material per unit area is proportional to the work due to the friction force: the removed material per unit area can be computed by adequately integrating the areal material ratio function (Abbott-Firestone curve) of the surface and can be associated with the amplitude roughness parameter; the work due to the friction force per unit area is proportional to the integral of the product of pressure and velocity in the time interval and can be derived from the process parameters by means of the Hertz theory. The model assessment was performed on ground glass flat samples polished with different operating parameters, mapping the surface roughness using an atomic force microscope (AFM). The developed model shows a satisfactory estimate of surface roughness evolution during the polishing process and confirms the experimental results found in the literature for the Preston coefficient. © 2008 Elsevier Ltd. All rights reserved.

Keywords: Abbott-Firestone , Glass , Material ratio , Polishing , Roughness , Surface texture

Previous work developed a knowledge-based method named Design GuideLines Collaborative Framework (DGLs-CF), adopted during product redesign and process reconfiguration and aimed at dealing and matching with particular manufacturing and verification technologies, according to ISO GPS concepts. Aim of present work is improving the role of the ISO GPS within the DGLs-CF, not only to raise coherence in terms of concepts, but to gain some important internal and external improvements for the DGLs-CF. The main activity toward achieving this goal is the formalization of DGLs-CF product features by means of the ISO GPS features. The procedure is proposed and the consequences of its application on the elements of the DGLs-CF are evaluated. A case of study as an example of application is also presented. A significant improvement in the DGLs-CF is realized, both in terms of knowledge structure and organization, and in terms of the possibility of interfacing it with other methodologies, tools, and environments. Copyright © 2008 by ASME.

Keywords: ISO GPS (geometrical product specifications) , ISO TC 213 , Knowledge-based engineering , Process reconfiguration , Product features , Product redesign

The LISA Technology Package (LTP) on board the LISA Pathfinder mission aims to demonstrate some key concepts for LISA which cannot be tested on ground. The mission consists of a series of preplanned experimental runs. The data analysis for each experiment must be designed in advance of the mission. During the mission, the analysis must be carried out promptly so that the results can be fed forward into subsequent experiments. As such a robust and flexible data analysis environment needs to be put in place. Since this software is used during mission operations and effects the mission timeline, it must be very robust and tested to a high degree. This paper presents the requirements, design and implementation of the data analysis environment (LTPDA) that will be used for analysing the data from LTP. The use of the analysis software to perform mock data challenges (MDC) is also discussed, and some highlights from the first MDC are presented. © 2009 IOP Publishing Ltd.

The data analysis of the LISA Technology Package (LTP) will comprise a series of discrete experiments, each focusing on a particular noise measurement or characterization of the instrument in various operating modes. Each of these experiments must be analysed and planned in advance of the mission because the results of a given experiment will have an impact on those that follow. As such, a series of mock data challenges (MDCs) will be developed and carried out with the aim of preparing the analysis tools and optimizing the various planned analyses. The first of these MDCs (MDC1) is a simplified treatment of the dynamics along the axis joining the two test masses onboard LISA Pathfinder. The validation of the dynamical model by predicting the spectra of the interferometer output data is shown, a prediction for the data analysis is calculated and, finally, several simulated interferometer data sets are analysed and calibrated to equivalent out-of-loop test mass acceleration. © 2009 IOP Publishing Ltd.

LISA Pathfinder (LPF) is a science and technology demonstrator planned by the European Space Agency in view of the LISA mission. As a scientific payload, the LISA Technology Package on board LPF will be the most precise geodesies explorer flown as of today, both in terms of displacement and acceleration sensitivity. The challenges embodied by LPF make it a unique mission, paving the way towards the space-borne detection of gravitational waves with LISA. This paper summarizes the basics of LPF, and the progress made in preparing its effective implementation in flight. We hereby give an overview of the experiment philosophy and assumptions to carry on the measurement. We report on the mission plan and hardware design advances and on the progress on detailing measurements and operations. Some light will be shed on the related data processing algorithms. In particular, we show how to single out the acceleration noise from the spacecraft motion perturbations, how to account for dynamical deformation parameters distorting the measurement reference and how to decouple the actuation noise via parabolic free flight. © 2009 IOP Publishing Ltd.

An extended work is in progress concerning the target development for the SPES (Selective Production of Exotic Species) project. The SPES will be an ISOL based facility (Isotope Separation On Line) in which a proton beam of 40 MeV and 0.2 mA impinges directly on a uranium carbide target. After the mass separation and re-acceleration on the experimental sites, the RIBs will have an intensity of the order of 109 pps (for 132Sn) and an energy up to 13 MeV/u. The new idea that characterize this project is the design of its target: we propose a target configuration capable to keep high the number of fissions, low the power deposition and fast the release of the produced isotopes.

During product development, the verification process should already be considered at the design phase to ensure that the characteristics of the product are measured effectively and reliably. Moreover, the verification process may prove more effective if the inspector is aware of the specific designer's intents. The development of the new ISO GPS (Geometrical Product Specifications) standards is mainly founded on these considerations. In accordance with the ISO GPS concepts, previous work developed a knowledge based system named Design GuideLines (DGLs). This system provides the designer with the knowledge concerning the manufacturing and verification procedures/tools and better links the manufacturing and verification processes to the designer's activities/needs. Further research then exploited the DGLs to discover the relations among product features determined by a particular manufacturing process. This work again uses the DGLs to prove that further relations among product features may also be determined by the verification process. This knowledge helps designers in understanding the consequences of the modifications applied to the product features required to improve the measurability of the product. Moreover, inspectors can better manage the verification procedure knowing these relations among the product features.

Keywords: Geometrical product specifications (GPS) , ISO/TC 213 , Knowledge based engineering (KBE) , Product features , Verification process

Recent analyses on the uninhabited aerial vehicle (UAV) accidents revealed that several kinds of human-system control problems occur in current UAV missions. Therefore, a design of the man-machine interface that allows for an efficient and effective interaction between the operator and the remote vehicle becomes one of the challenges in the development of more reliable UAVs. This paper presents a first implementation of an advanced interface for UAV ground control station based on a touch screen, a 3D virtual display, and an audio feedback message generator. The touch screen is used to send high level commands to the vehicle, the 3D virtual display provides a stereoscopic and augmented visualization of the complex scenario in which the vehicle operates, and the audio feedback message generator informs the operator about any change in operational scenario. The hardware/software architecture of the interface also includes a planning algorithm and a generic vehicle model. The interface has been tested by simulating several UAV missions. The results have shown that the interface requires an adequate level of workload to command the vehicle and allows the operator to build a good level of awareness of the state of the vehicle under his or her control, as well as of the environment in which it operates. © 2009 by the Massachusetts Institute of Technology.

The ability to perform autonomous mission planning is considered one of the key enabling technologies for uninhabited aerial systems. Subsequently, a big effort is made in the development of algorithms capable of computing safe and efficient routes in terms of distance, time, and fuel. In this paper an innovative 3-D planning algorithm is presented. The algorithm is based on considering the uninhabited aerial systems representation of real world systems as objects moving in a virtual environment (terrain, obstacles, and no fly zones), which replicates the airspace. Original obstacle avoidance strategies have been conceived to generate mission plans that are consistent with flight rules and with the vehicle performance constraints. Simulation test results show that efficient routes are computed in a few seconds.

The tool geometry is a crucial characteristic of the friction stir welding (FSW) process; its design is the key to the successful FSW application for a wide range of materials and thicknesses improving the weld strength and fatigue life. The present study investigates the influence of three shoulder geometries on the FSW joint performance, in terms of residual stresses state, microhardness profile and mechanical properties of 1.5 mm thick AA 6082-T6 FSW joints in the butt-joint configuration. The three tool geometries are characterized by three different shoulders: a shoulder with scroll, a shoulder with a shallow cavity, and a flat shoulder. Transverse and longitudinal tensile tests at room temperature were performed in order to evaluate the mechanical properties, respectively, of the joints and of the stirred zone, while the fatigue tests were performed transversally to the joint line. © KSME & Springer 2009.

Keywords: AA6082t6 , Fatigue , Friction stir welding , Residual stresses , Shoulder geometry

Metallic foams are new materials mainly produced by expansion in a proper chamber and mainly characterized by internal voids: a material characterized by a very low density is obtained in this way. A lot of foamed components are commonly produced, directly by injecting a gas or foaming agent into molten metal inside a closed die. However, secondary operations on these materials can play an important role in order to enhance the foam production flexibility. From the above considerations, the deformation behaviour of an aluminium foam was investigated by compression tests. The study compares three different numerical analyses highlighting their points of strength and weakness in order to verify their applicability in process design. More in detail, two models based on the implicit formulation were investigated; in one case, the billet material was set as porous object with the material density which was calculated and updated as part of the simulation. The second implicit analysis, instead, was built using the plastic material formulation; the porosity, in this case, was physically created introducing voids within the workpiece. The latter simulation class was carried out through an explicit investigation; an efficient model construction was proposed introducing spherical surfaces connected each other with plans. Experimental data were used to validate the calculated results and a discussion concerning the three different numerical analyses was finally reported. © 2008 Elsevier Ltd. All rights reserved.

This paper presents a novel 'touch and see' approach for interactive leaching of dynamic stress/strain distribution in engineering education. Our Augmented Reality application visualizes Finite Element Method (FEM) results overlaid over the real model. The user can interactively change the boundary conditions of the simulation and then evaluate the stress distribution in real time. Marker based video tracking is used to measure displacements while COMSOL Multiphysics solves the structural FEM analysis. A cantilever test case has been implemented and evaluated We describe the optimization solutions needed to achieve real-time simulation and precise and stable tracking. The presented system demonstrates significant educational benefits making the student's experience more attractive and effective. © 2009 TEMPUS Publications.

Keywords: Active learning , Augmented Reality , FEM , Tangible interfaces

Virtual Reality (VR) has quickly evolved over the last years in terms of technological and applicative dimensions, Human-Computer Interaction is particularly meaningful in the design activities involving multidisciplinary teamwork, collaborating to achieve a common task. It influences users behaviors, representational and communication modalities. A successful Collaborative Virtual Environment has to naturally support cognitive design actions while reducing time and costs. In this context, our research goal is to evaluate performances of different human-scale virtual environments in design situations involving multiple specialists with different knowledge and expertise. We proposed a protocol to highlight the main interaction styles in collaborative environments in order to assess how VR systems affect multidisciplinary cooperation. Experimental test cases are used to compare performances of virtual and physical prototypes in design reviews activities.

Keywords: Collaborative design , CVE , Multimodal interaction , Virtual Reality

Flexibility is the main keyword in order to face the rapid changing market requirements. Companies need methods and tools in order to implement flexibility over the whole product development process, from ideation to manufacturing. The proposed approach goes towards the concretization of the lean product design concept. It can be achieved if design alternatives and product modifications can be rapidly evaluated in terms of feasibility. resources. cost and time. The approach is based on a multilevel representation of the product structure. where functions. modules. assemblies and components are strictly interrelated. The complex representation requires suitable software tools in order to model and visualize the entire structure and support the easy user navigation. On the other hand it is necessary to define rules and operators to interact with the structure in order to make product changes and evaluate the possible impact. Finally. this system has to be integrated within the product development flow for exchanging data and information with CAD, PLM and ERP tools. In this paper the general approach is defined and the preliminary software solution is described.

Keywords: Change management , Change propagation , Lean design , Modularity

The promise of Virtual Reality in design environments is to facilitate the interaction with digital models and to enhance the results of design activity. Design education is one of the most recent and interesting applications. Thanks to technological advances in human-computer interfaces, Virtual Reality represents a new way to stimulate design students and to develop innovative teaching methods. The paper explores the impact of Virtual Reality technologies on design learning, with particular attention to mechanical product design. It is focused on the analysis of cognitive and technical aspects of learning processes and the definition of a proper evaluation protocol. The protocol is based on the classification of the most meaningful activities in mechanical engineering teaching and the identification of a set of metrics that enable to objectively evaluate the learning process. Assessing how VR supports design education, an experimental study is proposed. It is based on the comparison of three different approaches performed by two-dimensional drawings, by 3D CAD models and, finally, by virtual reality technologies. Copyright © 2009 by ASME.

It is well known that the global market is driving companies towards new productive paradigms oriented to product customization, agility and environmental sustainability. Companies have to face the problem of providing as much product variety as possible in order to rapidly satisfy a wide number of specific market segments. Even if the emerging automated agile production environments could enable them to manage product variety, in many productive fields, large waste streams, due to the practical difficulty of adapting the traditional production lines to product changes, are still present. At the same time a growing public concern for the environment, is forcing companies to investigate alternative uses for waste material. In this paper we present a practical example from the footwear industry in order to show how companies can successfully apply the concept of sustainable production taking into account the mass customization requirements but contemporarily reducing the material waste. The approach is focused on the combination in the same plant of two different production lines: one is dedicated to the primary production while the other uses the waste material to realize the secondary production. Copyright © 2008 by ASME.

The global market is evermore volatile and turbulent; it requires rapid responses to the emerging customers needs, also to unpredictable ones. Companies are forced towards a continuous research and innovation in terms of flexible technologies and processes in order to provide a high level of market adaptability. In this context, agile approaches, intended as a set of strategies to face the market variability, have to be investigated. They have to interest all processes related to the product development phase. This paper is focused on how to implement an efficient agile strategy in product design. The proposed approach is based on product modularity and on the integration of computer-aided design (CAD)-based tools to support feasibility analysis on virtual prototypes. It allows the concurrent management of possible changes in both product and process platforms by adopting virtual prototypes for performing simulations. The implemented platforms and the connected virtual prototype are structured according to modularity principles. The virtual prototype is defined as a collection of geometrical, functional, structural, manufacturing, environmental information, contained in the modules of the product and process platforms. An industrial example, belonging to the wellness production field (such as bathtubs and shower stalls), is described to validate the agile approach. It has been applied to solve a particularly meaningful problem: how to improve the bathtubs production process by reducing manufacturing and assembly costs while improving product customisability, eco-sustainability and quality. Once analysed, the context and the design constraints, in terms of cost, of environmental performance and, mainly, of aesthetic product features customisation, a new manufacturing process has been introduced based on the injection moulding technology instead of traditional thermoforming sheets.

Keywords: Aesthetic product development , Agile design , Customisation , Injection moulding

Purpose: The effects of light curing units (LCU) and energy doses on the chemical and physical properties of a dental composite were investigated. Methods: The effects on the chemical and physical properties of a bisphenol A diglycidylether methacrylate (Bis-GMA) based dental restorative material were evaluated through photospectrometry, differential scanning calorimetry, and mechanical measurements. Results: The light curing conditions associated with direct and indirect restorations were replicated in vitro using optical investigation techniques. A slight attenuation resulted independently of the LCU and a strong attenuation was measured for the cement luting a thick inlay, as well as for the deepest layer of a composite filling increment. Calorimetric measurements indicated that the curing degree is very sensitive to the light energy dose rather than to the LCU. Mechanical testing showed a transient phase during which properties increased. The delay of the composite in reaching adequate properties is strongly dependent on the energy dose. Conclusions: It is recommended that composites subject to unfavorable light curing conditions undergo a prolonged light curing process. © Società Italiana Biomateriali.

Keywords: Composite , Differential scanning calorimetry , Light curing , Mechanical properties , Restorative materials